Changes in Swift or JavascriptCore… | Apple Developer Forums

Changes in Swift or JavascriptCore causing crash?

I'm using JavascriptCore in a Swift app. For years I've had this logic:

public func doit(_ options: [String : Any]?) {
    jsValueOutline.invokeMethod("doit", withArguments: [options ?? [:]])
}

In particular the logic to turn nil options into a dictionary like this `options ?? [:]`.

Now this has started crashing for me. Seems maybe related to 10.15.4 ... though not entirely sure about that. Also is very odd in that I couldn't reproduce the problem for a few days... and now I can't not reproduce the problem. The crash stack looks like this:

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libobjc.A.dylib               0x00007fff6eb583c9 class_conformsToProtocol + 170
1   com.apple.JavaScriptCore       0x00007fff3858d6bd objectToValueWithoutCopy(JSContext*, objc_object*) + 77
2   com.apple.JavaScriptCore       0x00007fff3858cf3a objectToValue(JSContext*, objc_object*) + 74
3   com.apple.JavaScriptCore       0x00007fff3858ed17 -[JSValue invokeMethod:withArguments:] + 151

Good news is I can work around the problem by chaning my above code to:

publicfunc doit(_ options: [String : Any]?) {
    jsValueOutline.invokeMethod("doit", withArguments: [options as Any])
}

Note the change is to replace `options ?? [:]` with `options as Any`.

My question... what happened. Was I don't something wrong initially and it just happened to work? What changed to cause it stop working. Is my "fix" correct?

Thanks,
Jesse